7A3 ; 7C221 [Principles of interpretation: observance of good faith; Recourse to general principles on which Convention is based: good faith];

8C [Interpretation in light of surrounding circumstances];

18A [Formation of the contract (acceptance: time and manner): criteria for acceptance];

19A ; 19C [Reply purporting to accept but containing additions or modifications; Modifications that are material];

39A [Requirement to notify seller of lack of conformity: buyer must notify seller within reasonable time]